An endoscope or another medical instrument that must not be moved, at least at times, during a medical intervention can be held by a holding arm with lockable hinges and degrees of freedom. If the holding arm has a motor drive, the medical instrument can be moved by motor during the medical intervention. Lamps, light sources, monitors and other medical appliances whose position and orientation should be able to be modified, at least from time to time, can also be held by holding arms. Holding arms for these uses generally have several hinges that each facilitate a pivoting movement about one or more axes.
A medical holding arm should at the same time be as stiff as possible such that, with the hinges locked or the drives stopped, a medical instrument or a medical appliance can be held as still as possible even under the effect of an external force. Moreover, a medical holding arm should have a low mass in order to facilitate a movement with low forces and with low power. Moreover, the holding arm should be mechanically robust and easy to maintain, and it should be able to be produced cost-effectively, be easy to assemble and be able to be easily and completely cleaned.
An arm with several segments or portions each connected by hinges has been developed by Festo AG & Co. KG (www.festo.com/cms/de_corp/9770.htm). The ratio between mass and stiffness of the arm is still not optimal, however.